Half glossy half matt pot
You can define a mask to control where different textures etc are to be applied. A mask is usually a black and white image were black equals zero and white equals one. Connecting the mask into a mix shader node lets you choose between two different shaders, connected to a mix RGB node will choose between two colours.

Using a gradient texture to generate a mask.



With your example you can also connect the mask to the roughness input of your principled BSDF node.



For more control you can use texture painting to draw a mask on your model, then connect an image texture node in place of the above colour ramp.